Study of integrated protective immunity induced in rhesus macaques by the intradermal administration of a bivalent EV71-CA16 inactivated vaccine

Enterovirus type 71 (EV71) and coxsackievirus A 16 (CA16) are recognized as the major pathogens responsible for human hand-foot-mouth disease. To develop a bivalent EV71-CA16 vaccine, rhesus macaques immunized with two doses of this vaccine via the intradermal route were challenged with EV71 or CA16, and their clinical symptoms, viral shedding, neutralizing antibodies, IFN-γ-specific ELISpots, and tissue viral load were examined longitudinally. Specific immunity against EV71 and CA16 was observed in the macaques, which exhibited controlled proliferation of the EV71 and CA16 viruses and upregulated expression of immune-related genes compared with the controls. Furthermore, broad protection against EV71 and CA16 challenge without immunopathological effects was observed in all the immunized macaques. These studies suggest that the bivalent EV71-CA16 inactivated vaccine was effective against wild-type EV71 or CA16 viral challenge in rhesus macaques.     

A combination vaccine comprising of inactivated enterovirus 71 and coxsackievirus A16 elicits balanced protective immunity against both viruses

Enterovirus 71 (EV71) and coxsackievirus A16 (CA16) are the two major causative agents of hand, foot and mouth disease (HFMD), which is an infectious disease frequently occurring in children. A bivalent vaccine against both EV71 and CA16 is highly desirable. In the present study, we compare monovalent inactivated EV71, monovalent inactivated CA16, and a combination vaccine candidate comprising of both inactivated EV71 and CA16, for their immunogenicity and in vivo protective efficacy. The two monovalent vaccines were found to elicit serum antibodies that potently neutralized the homologous virus but had no or weak neutralization activity against the heterologous one; in contrast, the bivalent vaccine immunized sera efficiently neutralized both EV71 and CA16. More importantly, passive immunization with the bivalent vaccine protected mice against either EV71 or CA16 lethal infections, whereas the monovalent vaccines only prevented the homologous but not the heterologous challenges. Together, our results demonstrate that the experimental bivalent vaccine comprising of inactivated EV71 and CA16 induces a balanced protective immunity against both EV71 and CA16, and thus provide proof-of-concept for further development of multivalent vaccines for broad protection against HFMD.     

A novel inactivated enterovirus 71 vaccine can elicit cross-protective immunity against coxsackievirus A16 in mice

Hand, foot, and mouth disease (HFMD) is a highly contagious disease that mainly affects infants and children. Enterovirus 71 (EV71) and coxsackievirus A16 (CA16) are the major pathogens of HFMD. Two EV71 vaccines were recently licensed in China and the administration of the EV71 vaccines is believed to significantly reduce the number of HFMD-related severe or fatal cases. However, a monovalent EV71 vaccine cannot cross-protect against CA16 infection, this may result in that it cannot effectively control the overall HFMD epidemic. In this study, a chimeric EV71, whose VP1/210–225 epitope was replaced by that of CA16, was constructed using a reverse genetics technique to produce a candidate EV71/CA16 bivalent vaccine strain. The chimeric EV71 was infectious and showed similar growth characteristics as its parental strain. The replacement of the VP1/210–225 epitope did not significantly affect the antigenicity and immunogenicity of EV71. More importantly, the chimeric EV71 could induce protective immunity against both EV71 and CA16, and protect neonatal mice against either EV71 or CA16 lethal infections, the chimeric EV71 constructed in this study was shown to be a feasible and promising candidate bivalent vaccine against both EV71 and CA16. The construction of a chimeric enterovirus also provides an alternative platform for broad-spectrum HFMD vaccines development.     

Intradermal injection of a fractional dose of an inactivated HFMD vaccine elicits similar protective immunity to intramuscular inoculation of a full dose of an Al(OH)3-adjuvanted vaccine

Enterovirus 71 (EV71) and Coxsackievirus A16 (CVA16) are the two major causative agents of hand, foot and mouth disease (HFMD), which erupts in the Asia-Pacific regions. A bivalent vaccine against both EV71 and CVA16 is highly desirable. In the present study, on the bases that an experimental bivalent vaccine comprising of inactivated EV71 and CVA16 induces a balanced protective immunity against both EV71 and CVA16, we compare the immunogenicity and reactogenicity of one fourth of a full dose of an intradermal vaccine administered by needle-free liquid jet injector with a full dose of an intramuscular vaccine administered by needle-syringe in monkeys. The results suggest that intradermal injection of a fractional dose of an inactivated HFMD vaccine elicits similar immunogenicity and reactogenicity to intramuscular inoculation of a full dose of an Al(OH)₃-adjuvanted vaccine, regardless of whether monovalent or bivalent vaccines were used. Our results support the use of an intradermal bivalent vaccine strategy for HFMD vaccination in order to satisfy the requirements and reduce the costs.     

A virus-like particle based bivalent vaccine confers dual protection against enterovirus 71 and coxsackievirus A16 infections in mice

Enterovirus 71(EV71) and coxsackievirus A16 (CA16) are responsible for hand, foot and mouth disease which has been prevalent in Asia-Pacific regions, causing significant morbidity and mortality in young children. Co-circulation of and co-infection by both viruses underscores the importance and urgency of developing vaccines against both viruses simultaneously. Here we report the immunogenicity and protective efficacy of a bivalent combination vaccine comprised of EV71 and CA16 virus-like particles (VLPs). We show that monovalent EV71- or CA16-VLPs-elicited serum antibodies exhibited potent neutralization effect on the homotypic virus but little or no effect on the heterotypic one, whereas the antisera against the bivalent vaccine formulation were able to efficiently neutralize both EV71 and CA16, indicating there is no immunological interference between the two antigens with respect to their ability to induce virus-specific neutralizing antibodies. Passive immunization with monovalent VLP vaccines protected mice against a homotypic virus challenge but not heterotypic infection. Surprisingly, antibody-dependent enhancement (ADE) of disease was observed in mice passively transferred with mono-specific anti-CA16 VLP sera and subsequently challenged with EV71. In contrast, the bivalent VLP vaccine conferred full protection against lethal challenge by either EV71 or CA16, thus eliminating the potential of ADE. Taken together, our results demonstrate for the first time that the bivalent VLP approach represents a safe and efficacious vaccine strategy for both EV71 and CA16.     

Hepatitis B virus core particles containing multiple epitopes confer protection against enterovirus 71 and coxsackievirus A16 infection in mice

Human enterovirus 71 (EV71) and coxsackievirus A16 (CA16) are the two major causative agents of hand-foot-and-mouth disease (HFMD). To investigate novel combined vaccines to prevent EV71 and CA16 infection, we constructed chimeric virus-like particles (tHBc/SPA or tHBc/SP VLPs) displaying conserved epitopes of EV71 (aa 208–222 of VP1 and aa 248–263 of VP2) and CA16 (aa271-285 of VP1) using a truncated hepatitis B virus core carrier (tHBc). Immunization with the chimeric VLPs induced epitope- or virus-specific IgG and neutralization antibodies against EV71 and CA16 in the mice. Compared with inactivated EV71, the chimeric VLPs induced significantly increased Th1 cytokine (IFN-γ, IL-2) production and decreased Th2 cytokine (IL-4, IL-10) responses. Neonatal mice born to dams immunized with the recombinant particles were completely protected from lethal EV71 and partially protected from CA16 infection. Co-expression of the conserved human MHC class I CD4+ T cell epitope (aa248-263 of VP2) did not improve the antiviral immunity of the chimeric VLP vaccine in mice. Our results demonstrate that experimental combination vaccines comprised of EV71 and CA16 epitopes induce both humoral and cellular immune responses and therefore support further preclinical and clinical development of a bivalent VLP vaccine targeting both CA16 and EV71.     

Hexon-modified recombinant E1-deleted adenoviral vectors as bivalent vaccine carriers for Coxsackievirus A16 and Enterovirus 71

Hand, foot and mouth disease (HFMD) is a major public health concern in Asia; more efficient vaccines against HFMD are urgently required. Adenoviral (Ad) capsids have been used widely for the presentation of foreign antigens to induce specific immune responses in the host. Here, we describe a novel bivalent vaccine for HFMD based on the hexon-modified, E1-deleted chimpanzee adenovirus serotype 68 (AdC68). The novel vaccine candidate was generated by incorporating the neutralising epitope of Coxsackievirus A16 (CA16), PEP71, into hypervariable region 1 (HVR1), and a shortened neutralising epitope of Enterovirus 71 (EV71), sSP70, into HVR2 of the AdC68 hexon. In order to enhance the immunogenicity of EV71, VP1 of EV71 was cloned into the E1-region of the AdC68 vectors. The results demonstrated that these two epitopes were well presented on the virion surface and had high affinity towards specific antibodies, and VP1 of EV71 was also significantly expressed. In pre-clinical mouse models, the hexon-modified AdC68 elicited neutralising antibodies against both CA16 and EV71, which conferred protection to suckling mice against a lethal challenge of CA16 and EV71. In summary, this study demonstrates that the hexon-modified AdC68 may represent a promising bivalent vaccine carrier against EV71 and CA16 and an epitope-display platform for other pathogens.     

Chimeric enterovirus 71 virus-like particle displaying conserved coxsackievirus A16 epitopes elicits potent immune responses and protects mice against lethal EV71 and CA16 infection

Hand-foot-and-mouth disease (HFMD) is an infectious disease of infants and young children frequently caused by the enterovirus A species, mainly enterovirus 71 (EV71) and coxsackievirus A16 (CA16). In this study, we prepared the EV71 virus-like particle (EV71-VLP) and its chimeras using recombinant baculovirus (Bac-P1-3CD) co-expressing EV71 P1 (under polyhedrin promoter) and 3CD (under CMV-IE promoter) proteins in Sf9 cells. EV71-VLP chimera ChiEV71(1E)-VLP or ChiEV71(4E)-VLP displayed single CA16 PEP71 epitope in VP1 or four conserved CA16 neutralizing epitopes (PEP71 in VP1, aa136-150 in VP2, aa176-190 in VP3 and aa48-62 in VP4) by substitution of the corresponding regions of EV71 structure proteins, respectively. In mice, EV71-VLP and its chimeras elicited similar EV71-specific IgG and neutralizing antibody (NAb) titers compared to inactivated EV71. Expectedly, vaccination of ChiEV71(1E)-VLP or ChiEV71(4E)-VLP resulted in significantly increased CA16-specific IgG and NAb production and improved cross-protection against CA16 infection compared to EV71-VLP. Interestingly, the VLPs induced potent cellular immune responses and significantly decreased Th2 type (IL-4 and IL-10) cytokines secretion in the splenocytes of immunized mice compared to inactivated EV71 or inactivated CA16. Neonatal mice born to dams immunized with the chimeric VLPs or neonatal mice passively transferred with sera of immunized mice were completely protected from lethal EV71 challenge and partially protected from lethal CA16 infection. Our study provides a novel bivalent or multivalent vaccine strategy to prevent EV71 and related-enterovirus infections.     

Coxsackievirus A 16 infection does not interfere with the specific immune response induced by an enterovirus 71 inactivated vaccine in rhesus monkeys

Hand, foot and mouth disease is usually caused by enterovirus 71 (EV71) and coxsackievirus A 16 (CA16), which are members of the Picornaviridae family. In the present study, the characteristics of the immune response induced by an EV71 inactivated vaccine (made from human diploid cells) were explored in the presence of CA16 infection, based on the previously established neonatal rhesus monkey model. The typical clinical manifestations, including body temperature, viral viremia and virus shedding in the mouth, pharynx and feces, were characterized. A specific neutralizing antibody assay showed that the specific immune response induced by the EV71 inactivated vaccine was active against EV71 but not against CA16. No remarkable fluctuation in proinflammatory cytokine release was identified in the serum of immunized monkeys with EV71 vaccine and CA16 infections subsequently. The results showed that the specific immune response induced by the EV71 inactivated vaccine is effective against EV71 infection but is not affected by CA16 infection.     

A bivalent virus-like particle based vaccine induces a balanced antibody response against both enterovirus 71 and norovirus in mice

Noroviruses are the main cause of severe viral gastroenteritis, which results in estimated 200,000 deaths each year, primarily in children in the developing world. Genogroup II.4 (GII.4) strains are responsible for the majority of norovirus outbreaks. Enterovirus 71 (EV71), the leading causative agent of hand, foot and mouth disease, has recently been prevalent in Asia-Pacific regions, resulting in significant morbidity and mortality in young children. However, no vaccine is commercially available for either norovirus GII.4 or EV71. Recombinant virus-like particles (VLPs) derived from either GII.4 or EV71 have been shown to be promising monovalent vaccine candidates. In this study, we investigate the possibility to formulate a VLP-based bivalent vaccine for both norovirus GII.4 and EV71. The GII.4- and EV71-VLPs were produced in a baculovirus-insect cell expression system. A bivalent combination vaccine comprised of GII.4 and EV71 VLPs was formulated and compared with monovalent GII.4- and EV71-VLPs for their immunogenicity in mice. We found that the bivalent vaccine elicited durable antibody responses toward both GII.4 and EV71, and the antibody titers were comparable to that induced by the monovalent vaccines, indicating there is no immunological interference between the two antigens in the combination vaccine. More significantly, the bivalent vaccine-immunized mouse sera could efficiently neutralize EV71 infection and block GII.4-VLP binding to mucin. Together, our results demonstrate that the experimental combination vaccine comprised of GII.4 and EV71-VLPs is able to induce a balanced protective antibody response, and therefore strongly support further preclinical and clinical development of such a bivalent VLP vaccine targeting both norovirus GII.4 and EV71.     

Oral immunization of mice using transgenic tomato fruit expressing VP1 protein from enterovirus 71

Enterovirus 71 (EV71) causes seasonal epidemics of hand-foot-and-mouth disease associated with fatal neurological complications in young children, and several major outbreaks have occurred recently. This study developed an effective antiviral agent by transforming the gene for VP1 protein, a previously defined epitope and also a coat protein of EV71, into tomato plant. VP1 protein was first fused with sorting signals to enable it to be retained in the endoplasmic reticulum of tomato plant, and its expression level increased to 27 microg/g of fresh tomato fruit. Transgenic tomato fruit expressing VP1 protein was then used as an oral vaccine, and the development of VP1-specific fecal IgA and serum IgG were observed in BALB/c mice. Additionally, serum from mice fed transgenic tomato could neutralize the infection of EV71 to rhabdomyosarcoma cells, indicating that tomato fruit expressing VP1 was successful in orally immunizing mice. Moreover, the proliferation of spleen cells from orally immunized mice was stimulated by VP1 protein, and provided further evidence of both humoral and cellular immunity. Results of this study not only demonstrate the feasibility of using transgenic tomato as an oral vaccine to generate protective immunity in mice against EV71, but also suggest the probability of enterovirus vaccine development.     

Preclinical evaluation of recombinant HFMD vaccine based on enterovirus 71 (EV71) virus-like particles (VLP): Immunogenicity,efficacy and toxicology

Enterovirus 71 (EV71) is one of the major causative agents for hand, foot and mouth disease (HFMD) in children. Currently, three inactivated EV71 vaccines have been approved by Chinese government. We previously demonstrated that recombinant EV71 virus-like particles (VLP) produced in Pichia pastoris can be produced at a high yield with a simple manufacturing process, and the candidate vaccine elicited protective humoral immune responses in mice. In present study, the nonclinical immunogenicity, efficacy and toxicity of the EV71 vaccine was comprehensively evaluated in rodents and non-human primates. The immunogenicity assessment showed that EV71 VLPs vaccine elicited high and persistent neutralizing antibody responses, which could be comparable with a licensed inactivated vaccine in animals. The immune sera of vaccinated mice also exhibited cross-neutralization activities to the heterologous subtypes of EV71. Both passive and maternal antigen specific antibodies protected the neonatal mice against the lethal EV71 challenge. Furthermore, nonclinical safety assessment of EV71 VLP vaccine showed no signs of systemic toxicity in animals. Therefore, the excellent immunogenicity, efficacy and toxicology data supported further evaluation of the VLP-based EV71 vaccine in humans.     

环介导等温扩增法快速检测手足口病病原体

目的：建立逆转录（RT）-环介导等温扩增方法（LAMP）,以快速检测手足口病最重要的两种病原体：肠道病毒71型（EV71）和柯萨奇病毒A组16型（CA16）。方法：收集手足口病患儿咽拭子标本93份,针对EV71和CA16病毒的VP1基因特异性序列8个区域各设计6条LAMP引物,分别于63℃（EV71）、65℃（CA16A）扩增1 h,日光下观察结果,与实时荧光定量PCR比较检测特异性和敏感性。结果：EV71、CA16的LAMP最低检测限均为500拷贝/管,与对照病毒无交叉反应。93份标本中,RT-PCR方法检测显示EV71阳性44例,CA16阳性36例;RT-LAMP方法检测显示EV71阳性46例,CA16阳性36例,两种方法间比较差异均无统计学意义（P〉0.05）。结论：应用RT-LAMP检测手足口病病原体EV71、CA16快速、灵敏、经济、特异性高,适合在基层医疗机构推广应用。     

CA6阳性与EV71、CA16阳性手足口病患儿临床特征分析

目的 分析柯萨奇病毒A6型(CA6)阳性与肠道病毒71型(EV71)、柯萨奇病毒A16型(CA16)阳性手足口病患儿的临床特征.方法 选取商洛市中心医院2014年1月至2016年12月收治的1528例手足口病患儿,通过实时荧光定量聚合酶链反应法检测患儿肠道病毒核酸,以分析CA6、EV71、CA16三种病毒引起的手足口病患儿的临床特征.结果 在1528例手足口病患儿中,经病原学确诊出374例CA6阳性患儿、673例CA16阳性患儿、481例EV71阳性患儿.CA6阳性患儿发病平均年龄(t值分别为6.34、5.85)、齿龈部疱疹分布(χ2值分别为5.65、5.23)均低于CA16、EV71阳性患儿(均P<0.05),且发热分布均高于CA16、EV71阳性患儿(χ2值分别为8.56、8.23,均P<0.05).CA6阳性患儿C反应蛋白和WBC升高分布均高于CA16、EV71阳性患儿(χ2值分别为5.34、5.89;6.34、6.83,均P<0.05).结论 CA6已发展成一种手足口病患儿新型的流行病原,且其临床特征与因EV71及CA16引起的手足口病有所不同,可作为临床诊断的依据.     

广东省健康人群手足口病病原隐性感染状况调查

目的 了解广东省健康人群手足口病病原隐性感染情况.方法 在广东省7个市随机抽取7个年龄组健康儿童及成年人,采集粪便标本进行手足口病病原检测.结果 7个市共采集1285份样本,肠道病毒71型(EV71)阳性率为0.39％(5/1285),柯萨奇病毒A组16(CA16)阳性率为0.23％(3/1285),其他肠道病毒阳性率为7.00％ (90/1285).4～6岁年龄组EV71阳性率最高,为1.79％ (4/223),其次为0～3岁年龄组,为0.67％(1/223),其余年龄组均未检出EV71;只有4～6岁年龄组检出CA16,阳性率为1.35％ (3/223).所有EV71阳性标本均在本地户籍人群中检出,阳性率为0.47％(5/1063);CA16在本地户籍人群(0.19％)和外地户籍(0.85％)中均有检出,差异无统计学意义(P＞0.05).农村和城市EV71的阳性率分别为0.36％和0.54％,差异无统计学意义(P＞0.05);所有CA16阳性标本均在城市儿童中检出.结论 广东省健康人群中仅6岁以下年龄组检出EV71和CA16阳性,健康成年人中未检出EV71和CA16阳性,应重点对儿童尤其是学龄前儿童采取有效防控措施.     

2010年合肥儿童手足口病病例肠道病毒血清基因型分析

目的:对合肥地区2010年5~7月儿童手足口病流行期间的手足口病患儿进行病原学调查。方法:采集手足口病患儿的疱疹液、粪便、咽拭子进行病毒分离;分离的病毒接种非洲绿猴肾细胞(Vero)后待细胞病变(CPE)达到++++以上后提取RNA。分别用EV71和CA16的VP1基因的特异性引物进行RT-PCR鉴定,并根据血清型不同比较其临床特征。结果:77例患儿采集的标本中65例分离到病毒;经RT-PCR检测发现其中47例CA16阳性,18例为EV71,比例为2.6∶1。CA16感染和EV71感染在患者的年龄大小、症状轻重等方面无显著统计学差异。结论:手足口病患儿检测到的主要病原是CA16和EV71,两者感染对临床的影响无显著差异。     

2013-2014年泉州地区手足口病病原学监测结果分析

摘要:目的　了解2013-2014年福建泉州地区手足口病（HFMD）的病原学特征,为手足口病防治提供科学依据。方法　采集2013-2014年泉州市妇幼保健院·儿童医院收治的3839例手足口病患儿空腹静脉血标本,采用捕获法酶联免疫吸附技术检测肠道病毒71型（EV71-IgM）和柯萨奇病毒A组16型（CA16-IgM）。结果　3839例被检标本共检测出阳性标本2176例,阳性率为56.68%;其中32.87%（1262/3839）为EV71阳性,23.81%（914/3839）为CA16阳性,两者间阳性率差异有统计学意义（P＜0.05）。5岁以下HFMD患者3679例,占95.83%,其中1～2岁组患儿最多,占68.56%。3～4岁组患儿EV71阳性率（48.28%）和CA16阳性率（35.09%）最高。不同年龄组,EV71阳性率和CA16阳性率均存在统计学差异（P＜0.05）。手足口病发病随季节而发生变化,不同月份EV71和CA16阳性率均存在统计学差异（P＜0.05）。发病以4-7月份为主,占56.37%,2014年9-10月份发病率出现一定程度反弹。结论　2013-2014年泉州地区手足口病肠道病毒EV71型的阳性检出率高于CA16型,4-7月份为发病高峰期,5岁以下儿童为高发人群,其中1～2岁组手足口患儿居多,而3～4岁组病毒阳性率最高,需引起重视。     

Immunization with virus-like particles of enterovirus 71 elicits potent immune responses and protects mice against lethal challenge

Enterovirus 71 (EV71) is an etiologic agent responsible for seasonal epidemics of hand-foot-and-mouth disease and causes outbreaks with significant mortality among young children. To develop the vaccine, we have produced and purified the EV71 virus-like particle (VLP) that resembles the authentic virus in appearance, capsid structure and protein composition. In this study, we further evaluated the potential of VLP as a vaccine by comparing the humoral and cellular immune responses elicited by the purified VLP, denatured VLP and heat-inactivated EV71 virus. After immunization of BALB/c mice, EV71 VLP induced potent and long-lasting humoral immune responses as evidenced by the high total IgG titer and neutralization titer. The splenocytes collected from the VLP-immunized mice exhibited significant cell proliferation and produced high levels of IFN-gamma, IL-2 and IL-4 after stimulation, indicating the induction of Th1 and Th2 immune responses by VLP immunization. More importantly, the VLP immunization of mother mice conferred protection (survival rate up to 89%) to neonatal mice against the lethal (1000 LD(50)) viral challenge. Compared with the VLP immunization, immunization with denatured VLP and heat-inactivated EV71 elicited lower neutralization titers and conferred less effective protection to newborn mice, although they induced comparable levels of total IgG and cellular immune responses. These data collectively indicate the importance of the preservation of VLP structure and implicate the potential of VLP as a vaccine to prevent EV71 infection.     

EV71感染与固有免疫应答相互作用关系的研究进展

肠道病毒71型（enterovirus 71,EV71）是引起手足口病的主要病原体之一,可引起严重并发症,致残率及病死率较高,是严重危害婴幼儿健康的重大公共卫生问题之一。EV71感染后,宿主启动固有免疫应答抵御感染,而病毒则通过一系列机制逃逸固有免疫的抑制和清除,二者之间存在着博弈关系,两者斗争的结果与EV71感染所致手足口病的病程和结局密切相关。本文就近年来EV71感染与固有免疫应答之间相互作用关系的研究进行综述,旨在为后续研究的深入开展和新型疫苗、药物的研发提供线索和思路。     

Recombinant porcine lactoferrin expressed in the milk of transgenic mice protects neonatal mice from a lethal challenge with enterovirus type 71

The human Enterovirus genus of the piconavirus family causes most of the febrile illnesses that affect children during the summer season in Taiwan. Enterovirus type 71 (EV71) plays a key role in patients with hand-foot-and-mouth disease (HFMD) combined with severe paralysis or encephalitis. It is important to find a method for preventing infection with EV71 since there is no antiviral agent or vaccine for humans. In this study, we developed a transgenic mouse model for demonstrating the protective effects of recombinant lactoferrin (LF) against EV71 infection. Transgenic mice carrying alpha-lactalbumin-porcine lactoferrin (alphaLA-pLF) and BALB/c wild-type mice were subjected to EV71 inoculation. First, we analyzed the expression efficiencies of recombinant pLF (rpLF) in hemizygous and homozygous transgenic mice. Following EV71 inoculation on the 4th day of life, pups ingesting transgenic milk showed the significantly higher survival rate and heavier body weight compared to wild-type mice. RT-PCR analysis for EV71 viral RNA showed that the recombinant pLF had a blocking effect on EV71 infection. Our data suggest that oral intake of pLF-enriched milk exhibited the ability to prevent infection with EV71. The study also provides an animal model for validating the protective effects of pLF.